1. Field of the Invention
This invention relates to bis(aminostyryl)benzene compounds which are suitable for use as an organic luminescent material capable of developing a desired luminescent color and to synthetic intermediates thereof. The invention also relates to a process for preparing such compounds and intermediates as mentioned above.
2. Description of the Related Art
As a candidate for flat panel displays which make use of spontaneous light, have a high response speed and has no dependence on an angle of field, attention has been recently paid to organic electroluminescent device (EL device) and an increasing interest has been taken in organic luminescent materials for the EL device. The first advantage of the organic luminescent material resides in that the optical properties of the material can be controlled, to an extent, depending on the molecular design, so that it is possible to realize a full color organic luminescent device wherein three primary color luminescences of red, blue and green can be all ensured by use of the respective organic luminescent materials.
The bis(aminostyryl)benzene compound of the following general formula [A] is able to develop blue to red strong luminescence in a visible region depending on the type of introduced substituent: 
wherein Ar represents an aryl group which may have a substituent, Ra and Rb, respectively, represent a hydrogen atom, a saturated or unsaturated hydrocarbon group, an aryl group which may have a substituent, a cyano group, a halogen atom, a nitro group or an alkoxy group and may be the same or different. Hence, this compound is utilizable not only as a material for an organic electroluminescent device, but also in various fields. These materials are sublimable in nature, with the attendant advantage that they can be formed as a uniform amorphous film according to a process such as vacuum deposition. Nowadays, although optical properties of a material can be predicted to some extent by calculation of its molecular orbital, it is as a matter of course that a technique of preparing a required material in a high efficiency is most important from the industrial standpoint.
Up to now, a great number of compounds including those of the above general formula [A] have been prepared for use as an organic luminescent material. The fluorescence or luminescence of these materials mostly covers blue to green colors, and only a few of materials which develop yellow to red luminescence has been reported [Technical Investigation Report of The Association of Electric Information Communication, Organic Electronics, 17, 7 (1992), Inorganic and Organic Electroluminescence 96 Berlin, 1010(1996) and the like]. In addition, there has never been established any highly efficient process of preparing such materials.
Accordingly, an object of the invention is to provide compounds, which are suitable for use as an organic luminescent material capable of developing intense luminescence which is particularly yellow to red in color, and synthetic intermediates thereof.
Another object of the invention is to provide a process for preparing the compounds and their intermediates in a high efficiency.
We made intensive studies in order to solve the above-stated problems of the prior art, and as a result, found that bis(aminostyryl)benzene compounds of the general formulas [I], [II], [III] and [IV] are able to develop intense luminescence and are suitable as a luminescent material of yellow to red colors. At the same time, we established general and highly efficient preparation thereof.
More particularly, there is provided, according to the invention, a bis(aminostyryl)benzene compound of the following general formula [I], [II], [III] or [IV] (which may be hereinafter referred to as inventive compound): 
wherein R2 and R3 independently represent an unsubstituted aryl group, and R1 and R4 independently represent an aryl group represented by the following general formula (1): 
in which R9, R10, R11, R12 and R13 are independently groups, which may be the same or different, provided that at least one of them is a saturated or unsaturated hydrocarbon oxy group or a hydrocarbon group having two or more carbon atoms, and R5, R6, R7 and R8 independently groups, which may be the same or different, provided that at least one of them represents a hydrogen atom, a cyano group, a nitro group or a halogen atom (which means F, Cl, Br or I herein and hereinafter): 
wherein R14, R15, R16 and R17 may be the same or different and independently represent an aryl group of the following general formula (2): 
in which R22, R23, R24, R25 and R26 are independently groups, which may be the same or different, provided that at least one of them represents a saturated or unsaturated hydrogren oxy group or a hydrocarbon group, and R18, R19, R20 and R21 are independently groups, which may be the same or different, provided that at least one of them represents a hydrogen atom, a cyano group, a nitro group or a halogen atom: 
wherein at least one of R27, R28, R29 and R30 represents an aryl group of the following general formula (3) and the others represent an unsubstituted aryl group: 
in which R35, R36, R37, R38 and R39 are independently groups, which may be the same or different, provided that at least one of them is a saturated or unsaturated hydrocarbon amino group, and R31, R32, R33 and R34 are independently groups, which may be the same or different, provided that at least one of them is a hydrogen atom, a cyano group, a nitro group or a halogen atom: 
wherein R41 and R42 may be the same or different and independently represent an aryl group of the following general formula (4): 
in which R48, R49, R50, R51 and R52 may be the same or different and independently represent a hydrogen atom, or at least one thereof is a saturated or unsaturated hydrocarbon oxy group or a hydrocarbon group, and R40 and R43 may be the same or different and independently represent an aryl group of the following general formula (5): 
in which R53, R54, R55, R56, R57, R58 and R59 may be the same or different and independently represent a hydrogen atom or at least one thereof represents a saturated or unsaturated hydrocarbon oxy group or a hydrocarbon group, and R44, R45, R46 and R47 are independently groups, which may be the same or different, provided that at least one of them is a hydrogen atom, a cyano group, a nitro group or a halogen atom.
The inventive compounds can be effectively utilized as an organic luminescent material capable of developing yellow to red luminescence. These compounds are ones which have a high glass transition point and a high melting point and are excellent in electric, thermal and chemical stabilities. In addition, they are amorphous in nature, is capable of readily forming a vitreous state and may be subjected to vacuum deposition.